A fluid operated wrench for tightening or loosening a threaded connector without turning the wrench around comprises fluid operated cylinder and piston unit having an axis, a support including a first support portion for supporting the cylinder and piston structure, and a second support portion extending substantially perpendicularly to the axis of the cylinder and piston structure, ratchet held by the first support portion and having a ratchet axis extending substantially perpendicular to the latter, reversable transmission intermediate the cylinder and piston unit and the ratchet structure to drive the latter in one or the opposite direction during movement of the piston, structure connected to the ratchet structure for engaging a threaded connector to be turned, whereby during turning of the threaded connector in one direction a force is created tending to turn the support structure in the opposite direction, a reaction member arranged to abut against a stationary object, and structure for adjustably attaching the reaction member to the second support portion so that the reaction member is supported by the second support portion and can be adjusted to abut against a stationary object in any position within a circle of 360.degree. around the ratchet axis, in any position within a circle of 360.degree. around the ratchet axis, including turning the reaction member by 180.degree. to abut against a stationary object located at either side of a threaded connector to be turned while the support structure remains stationary.